The Mozilla Project has posted the first beta of Firefox 3.1 for Mac, Linux, and Windows. Version 3.1 is built on Gecko 1.9.1, improves Web standards support, adds a Text API to the Canvas Element, supports border images and JavaScript query selectors, and claims to improve the URL bar (though they've been missing a lot of low-hanging fruit there for years, so I'm skeptical.) This beta adds:
Windows 2000 or later and Mac OS X 10.3.9 or later or Linux are required. Windows 98 and earlier and Mac OS X 10.2 and earlier are no longer supported. Final release is not expected until next year.